Using PACs and PLCs for Data Acquisition, Logging & Analytics

General-purpose machine controllers, whether they are PACs, PLCs, or PC-based controls, are offering more support for data acquisition, data logging, and analysis than ever before. But the key will be how systems engineers use these more expansive data sets to improve machine performance.

"PLCs and PACs are becoming more powerful by offering more memory and more processing power," Jeff Payne, product manager for PLC, IO, and PC-based controls at AutomationDirect, told us. "The availability of data in machine processes and machinery has always been a necessity in testing applications, but now data collected by process engineers and manufacturing managers is being used to improve the process in real-time."

Modern and powerful PLCs and PACs can perform many of the data acquisition functions formerly reserved for SCADA, PC-based, and other control systems.(Source: AutomationDirect)

Programmable automation controllers (PACs) have become the convergence or gray area between programmable logic controllers (PLCs) and PC-based controllers, Payne said. PACs were one of the first rack-based control systems to offer the higher processing power and enhanced memory capabilities that fit well into applications where data acquisition can be applied. The physical memory space and processing power of these devices not only can handle machine control but also can collect and analyze data and apply changes to the actual machine control in real-time. The line between PLCs and PACs is blurring. PLCs themselves are becoming more powerful and offer more of the features that PACs implemented early on.

What type of control technology to implement generally depends on the user and their specific objectives. Higher-end PLCs provide a lot of these same features, but PACs have been instrumental in breaking down the barrier to more data acquisition, data logging, and advanced analytics. They are designed specifically to bring all of these systems together in one complete unit and offer users one small footprint and complete platform to provide sensing, signal conditioning, measurement, and analysis all done within the one controller.

Data collection has always been a key aspect of lab testing applications, but now the trend is toward an application base that is broadening out into mainstream process and manufacturing environments. Manufacturing systems themselves have so much data to provide that, once an engineer has an opportunity to collect the data, it often offers an opportunity to improve the process dramatically. For example, collecting real-time temperature data from a plastic injection molding machine or a tempering furnace allows engineers to identify trends, monitor the process more closely, and correlate results to product quality.

Specific applications (such as pharmaceutical or solar cell manufacturing) collected large amounts of data in the past, but with the emergence of the Internet of Things, such collection efforts seem more widespread. As more engineers realize that these capabilities are available, especially in smaller controllers (as an alternative to more expensive data logging or SCADA software), they are taking advantage of capabilities being built into the controllers themselves.

Data logging and storing large amounts about the manufacturing process itself is another target for these systems. These controllers now typically implement inexpensive memory devices such as an SD card or a removable USB drive, which typically offers 16 or 32 GB of storage on the controller itself. In these applications, machine controllers were previously limited by the restricted memory space in the controller and an inability to expand that memory or store on an external device.

Ethernet networking and support for a variety of machine control protocols is another plus in these systems. Another good thing is that PACs often offer some type of web server, so the controller can be networked, and data files are available through a web browser. Users can tap into the log files, even if they are on the physical USB device, but are accessible through the built-in web server of the controller itself.

Now that it is becoming the standard for industrial control, Ethernet networking will provide a potent solution for even more sophisticated data analysis applications. But it will be interesting to see how machinery builders can leverage this process data into a higher level of useful analysis.

Presentation of the data is a big part of that equation, and the majority of users are still using Excel as the primary analysis tool. Using the CSV or comma separated variable data type is good in the sense that it makes it easy to access data, but how engineers are manipulating that data is a completely different topic, because there are so many ways to view the data and correlate the data to provide useful information.

TJ, I agree with you that these capabilities have been around for awhile, and actually go way back further than the introduction of PACs. Making it easy to collect information is one step, and also for users to gain confidence that the machine controller has both the processing power and flexibility to do multiple tasks without creating problems with machine control.

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